Jack Taylor hit his fifth first-class century as Gloucestershire ran up 343 for eight on the opening day of their Specsavers County Championship Division Two match with Worcestershire at Cheltenham.
Dropped on 16, Taylor went on to a 122-ball hundred and was still there at the close on 118, having hit 16 fours and a six.
Chris Dent and Phil Mustard, with 65 and 50 respectively, were the other main contributors for the hosts, who had to recover from losing Cameron Bancroft to the first ball of the match.
Ed Barnard was the pick of the Worcestershire attack, taking 4-67. But they will have been disappointed with their day, having reduced Gloucestershire to 87-4 by lunch.
Visiting skipper Joe Leach exercised his right to field and then struck with his opening delivery as Bancroft was lbw only half forward.
Will Tavare (21) got the scoreboard ticking with an early six over square-leg off John Hastings and added 53 with Dent before being well caught low down to his right by wicketkeeper Ben Cox, edging Leach (2-67).
Gareth Roderick had made only 11 when he totally miscued an attempted hit to leg and offering a simple catch to point to give Barnard his first wicket with the total on 79.
And Gloucestershire looked in trouble when off-spinner George Rhodes struck in his opening over shortly before lunch, Cox taking the catch as Graeme van Buuren, on one, edged an attempted cut.
The afternoon session saw the home side fight back with the sun shining. Dent, who had batted steadily through the morning, reached his fifty off 103 balls, with six fours.
But the left-handed opener went with the score on 129, lbw to a ball from Barnard that appeared to keep a bit low.
If there was a pivotal moment, it came with the Gloucestershire total on 147-5 as Taylor, who had survived a couple of edges, was dropped at third slip by Joe Clarke off Josh Tongue, the catch arriving at a comfortable height.
Taylor responded to his reprieve with a straight six off Rhodes and went to a 51-ball half-century as he and Mustard took the score to 221-5 at tea.
Home skipper Mustard followed him to fifty at the start of the third session, having faced 125 balls, but was out in the same over, bowled driving at Barnard.
When Kieran Noema-Barnett was caught behind off Tongue for a duck it was 234-7 and Worcestershire appeared to have regained control, but Craig Miles then joined Taylor and cracked a crucial 39.